Britney Spears, who was characterized as mentally unsound by her mom's legal team recently, was tapped by Los Angeles' KIIS FM to guest-host with Ryan Seacrest at this weekend's annual Wango Tango concert at the Staples Center.

Fans enjoyed a diverse roster, according to MTV News, including performances from Jennifer Lopez, Ke$ha, Selena Gomez, Cobra Starship, T-Pain, Lupe Fiasco, Cody Simpson, Far East Movement and 'Glee' star Matthew Morrison.

Ke$ha brandished her famous glitter gun for her second year appearing at Wango Tango. And J.Lo rocked her spangled catsuit, but was hampered by a sudden, serious audio glitch (video after the jump). For a long stretch of her single 'On the Floor,' the 'American Idol' star had to improvise booty bumps after her mic went out.